Hydraulic device



M. J. CLARK HYDRAULIC DEVICE Filed May 4, 1936 2 Sheets-Sheet l A TTORNEYS.

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July 18, 1939. M. J. @MRM HYDRAULIC DEVICE Filed May 4. 1956 2 Smets-Sheet 2 Patented July 18, "1939 UNITED STATES PATENT OFI-ics 17 Claims.

This invention relates to hydraulic devices and more particularly to such hydraulic devices as may be adapted for usein connection with various types'of machine tools and other contrivances for effectinghydraulic feeds and controls in the operation thereof.

In connection with the devices of the above character, it is desirable to have pumps which, while operating substantially at constant speeds, usually from mechanical drives, can quickly vary their rate of discharge in order to produce a rapid advance of the actuated member through a considerable distance into a certain position, a motion thereof through a desired distance at a slow predetermined rate, and a rapid return of said actuated member to its original position. For instance, in connection with a drill press, it is desirable to have an oil 'pump capable of varying its discharge in such a way as to effect, when desired, a rapid movement of the drill toward the work, a slow feeding of said drill into the work to a desired depth, and a rapid return thereof to its starting position. In connection with suchl devices it has been found highly undesirable to have a pump the rate of intake of which is constant, while the control of its rate of discharge is accomplished through by-passing the surplus amount of fluid into the escape conduit, since in such case the pump will always operate at its full capacity consuming maximum power. Moreover, throttling the liquid fluid, that is, forcing the same through a restricted orifice under a high pressure, produces excessive heating of the fluid, making it impossible to operate such pumps on a limited amount of fluid and rendering them inapplicable to uses with machines in which only a limited space may be allowed for storing the fluid.

It is apparent, therefore, that a pump in which `the rate of discharge equals or substantially equals the rate of intake will possess many advantages in connection with the above uses, since it will effect a large economy in the power consumed, because such a pump will not operate at Vits maximum capacity at all times. As apconsequence the life of the pump will be prolonged, permitting operatlon of comparatively large machines on a very limited amount of oil and preventing heating of the oil or of other fluid used.

Accordingly, itis an important` object of the present invention to provide` a hydraulic device which may be adapted for use with machine tools and other contrivances for effecting hydraulic feeds and controls, and which includes a positive acting pump in which the rate of discharge is controlled by the change of volumetric displacement of the pump, and particularly in which said change of volumetric displacement is effected automatically by novel means responsive to pressures resulting from the operation of the pump, whereby such rate of discharge as is necessary for producing a desired type of movement of the hydraulically actuated member is /automatical- 1y effected. l Annther object of the present invention is to provide a hydraulic pump adapted to pump the fluid only in such quantities as are necessary for effecting the desired movements of the hydraulically actuated member, thuseffecting considerable economy in power consumption, and permitting operation of large machines on a very limited amount of fluid without the danger of excessive heating of said fluid.

A further object of the invention is to provide a rotary oil pump for use in hydraulic feed and control devices, in which the amount of eccen-l tricity of the rotor, determining the discharge of the pump, is automatically controlled by the 'pressures resulting from the operation of the pump and is varied so as to effect changes in the rate of discharge from the no-discharge" to the discharge corresponding to the maximum capacity of the pump.

A still further object of the invention isf to provide a novel device for effecting hydraulic feeds and controls, having a metering device adapted to be operated by the pump, which metering device will operate to relieve the back pressure acting upon the hydraulically actuated piston, determining therebyy the rate of vfeeding movement of said piston and themember connected thereto.

A still further object of the invention is to provide a metering device of the character mentioned, which has regulating means whereby the rate of its operation is regulated and changed as desired.

A still further object of the invention is to provide a device for effecting hydraulic feeds and controls, having a hydraulically balanced, manually` operated controlvalve, the shifting of which into a respective position for rapid move ment of the operating piston directs the discharging fluid into the operating cylinder and at 'a proper side of the piston arranged therein, con,-v necting at the same time the space on the opposite side of the piston with a free escape opening and at the same .time cutting communication of the displacement-decreasing cylinder with said opposite side. Y

It is a still further object of the invention to provide a control valve of the above character which operates, when set for feed movement of the operating piston, tes-establish a connection 5 of the displacement-controlling cylinder with the back vpressure side of the operating cylinder.

A still further object of the invention is to provide a rotary pump having a rotor-encircling ring of constant, built-in eccentricity, the volum metric displacement of said pump being varied from" zero to the full' capacity displacement by changing the position of said rotor vencircling ring with respect to the intake and discharge vanes of the pump. l

A still further object of the invention is to provide a pump of the character mentioned in the preceding paragraph, having means responsive to pressures resulting from the-operation of they pump for changing the position of said rotorencircling rlngin accordance with said pressures.

Still anothenobject of the invention is to provide a hydraulic pump having a concentric rotorencircling ring and means responsive to the Pressures resulting from the operation of said pump g5 for moving' said concentric rotor-encircling ring into aposition of greater eccentricity when said means are exposed to said pressures.

Other objects and advantages of the present invention-will appear more fully hereinafter from a consideration of the following description and appended claims, reference being had to the accompanying drawings wherein two embodiments of the invention are illustrated.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a view illustrating diagrammatically the hydraulic circuit embodying the present' invention, and showing the pump in transverse 4 0 vertical section/.the control valve and the operating cylinder being shown in longitudinal cross' Fig. 6 is a view similar to that of Fig. l illus-` trating a modified form of my invention.

Fig. 'l is a` longitudinal sectional view of the pump of modified construction, section being` taken on the line 1--1 of Fig. 6.

Fig. 8 illustrates the position of the control valve, stop valve, and the ypump rotor, for. idling operation of the pump of Fig. 6.

Before explaining in detail the` present invention it is to be understood that the invention is not limited in its applicationto the details of construction and arrangement of parts illustrated /in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it 79 is to be understood that 'thephraseology or terminology employed herein is for.the purpose of' description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements ofthe prior art.

75 In the drawings there is mum-ated, by way of example, a hydraulic device embodying my'invention which comprises a positivevpump of rotary type, designated generally by the numeral 20, a

manually or otherwise operated control valve, designated generally by the numeral Ill, and a hydraulically actuated member represented by a piston Gl arranged in a suitable operating cylinder Sli. Av piston rod i2 is connected to the member, the movement of which it is desired tov control, such asa drill, a cutting tool of whatever kind, a 'control lever, and the like. Said pump, control valve. and the operating cylinder are interconnected by means of a number lof suitable conduits. The control valve 4U is provided with a number of escape outlets leading into an oil storage tank (not `shown). The control valve 40 may be manually operated with the aid of a suitable lever. The pump 2l is provided with means for changing its volumetric displacement, which means are automatically regulated by the hydraulic pressure resulting in the circuit because of the operationof the pump when the control valve is set in. respective operative positions. When the control valve is set for rapid advance of the hydraulically actuated piston, the pump operates at its largest displacement and, consequently, at its full capacity and is pumping oil into the operating cylinder 60 and to the desired side of said piston (pressure side), while the oil f` from the operating cylinder on the opposite side of the piston (back-pressure side) is allowed by the control valve to escape freely into the storage tank. For eifectinga rapid return movement of the operating piston, the control valve is put in such a position that the oil is pumped into the back-pressure space of the l,operating cylinder, while the oil from the pressure side of the cylnder is allowed to escape freely into the oil storage tank. For effecting a slow movement of the actuated member, that is to say, the feed movement thereof, the control valve is `put in such a position that while the oil is pumped into the pressurel space of theI operating cylinder, the oil from the space on the back-,pressure side of the piston is prevented from escaping, thus building up back-pressure resisting the advance movement of the operating piston 6I. In this condition, the only escape for the oil contained in the back-pressure space of the cylinder is through a special metering device, indicated generally in the drawings by the numeral 10, which device meters or measures oil the oil at a predetermined rate, thus relieving the back-pressure on the piston 6i and allowing its advance movement of a predetermined rate. In this condition, the increased back-pressure in the cylinder 60 is allowed by the control valve l0 to operate upon special means which decrease the displacement ofthe pump substantially in inverse proportion toy said back-pressure. Thus, in this condition the pump is operating at its partial capacity and is pumping only a very limited quantity of oil.

In the present embodiment the volumetric displacement of the pump is varied by affecting the eccentricity of the rotor-encircling ring of the rotary pump. In the preferred structure the eccentricity of the rotor-encircling ring is constant, and the control of displacementis effected by changing the position of the line of eccentricity of said ring with respect to the concentric rotor of the pump. In the modified structure the control of the pump displacement is effected by changing the amount of eccentricity between the fixed axis of the concentric rotor and the axis of the bodily movable rotor-encircling ring. It is an important feature of my invention that con trol of the position'of eccentricity in the pre ierred structure,` as Wellas the control of the amount of eccentricity in the modified structure, is effected automatically with the aid of means responsive to the pressures resulting from opera'- tion of the pump. It is to be expressly understood that I do not desire to limit myself either to controlling pump displacement Vby affecting apump body 2| which supports a rotor shaftI and is bored concentrically therewith. Within said pump body 2| there is arranged a rotor-encircling ring 22 fitting by its turned cylindrical surface` 23 into the concentric bore of saidpump body 2|. Said concentric surface of the ring 2-2 is milled or, cut to form a gear portion 23a. The

inner surface 24 of said ring 22 is bored eccen# trically withrespect to its outervsurface 23 and,

Y consequently, to the center line of the rotor shaft 1 23a of the rotor-encircling ring 22.

25. The rotor shaft 25 carries a concentrically mounted rotor 26. The body of the rotor 26 is provided with a plurality of longitudinal radial slots, such as shown at 21, with slidable blades or paddles, such as shown at 28. The rotor,26 revolves between plates 29 and 30 arranged within the pump body. The plate 29 is provided with two arcuated slots 3| and 32, the 'slot 3| communicating with the intake conduit II, and the slot 32 communicating with the discharge conduit |2 leading to the control valve 4|l.

Suitably ailixed to or` formed yintegrally with the pump body 2| is a displacement-controlling cylinder 34 which has a piston 35 operatively arranged therein. The piston 35 has al rack 36 attached to it, which rack engages the gear portion The closed end 31 ofthe cylinder 34 houses a suitable `helical spring 38vbearing against the end of the rack 36 and tending to keep the piston 35 in its fully extended position, and consequently acting in opposition to piston 35. .The cylinder 34 communicates with the control valve 40 through ,a conduit I5. i 1

In the present embodiment the gear portion 23a is formed on the outside surface of the rotorencircling ring 22. However, I do not desire to limit myself to such construction, since suchgear may be Iformed at'any por-tion of said ri'ng where l its engagement with the rack is practical.

The rotor shaft 25 is provided with a suitable drive, such as a gear 33. Rotation of the shaft 25 and therotor 26 :at a speed above a certain minimum operates to push the' blades or paddles 23 outwardly. Sliding outwardly in the radial slots 21 said blades engage the eccentrically bored surface 24 of the rotor-encircling' ring 22. The pockets which are thus formed by the blades 28 change their volumetric capacity as they are moving along the arcuated slots 3| and 32. Considering the clock-wise direction of rotation of the rotor 26, it will be appreciated -from an examination of Fig. 1 that as a respective pocket reaches the slot 3|, it begins to increase its volumetric displacement, and a partial vacuum is, therefore,

Y created therein. Since the slot 3| communicates with the intake pipe |I, the pockets will draw in the oil as they move along the slot 3| in the clock-wise direction.. At the moment when a. re-

spective pocket loses its communication with the vslot 3| and, consequently, with -the intake pipe II, it is in a condition of its maximum displacement for the conditions oi' thatparticular revolution and, consequently, it holds the maximum quantity of oil which it is capable of holding under those conditions. As the' pocket continues toy move in the clock-wise direction, its volumetric displacement begins to decrease and the oil which it contains is gradually forced out into the Slot 32 and therethrough into the discharge conduit I2. The distance between the extremities of the slots 3| and 32 is made greater than the distance between two adjacent blades, in order to prevent short circuiting of said slots by one pocket.

For producing the greatestv aggregated volumetric displacement of the pump 20, the ring 22 is setin such a position that the line of eccentricity a-a of said ring passes through the points intermediate the extremities of the slots 3| and 32. Such a position of this ring 22 is ilu lustrated in the Fig. 1. If the ring 22 is rotated in a clock-wise direction within the pump body 2| through an angle of 90, and is thus brought into the position shown in Fig. 3, the line of eccentricity of the ring 22 a-a will assume the position in which it is passing through the middle points of the slots 3| and 32. that in this position of' the pump ring, as the pockets move in the clock-wise'direction, their displacement will be decreasing up to the middle point of the slot 3|, and increasing in cor-responding proportion after passing said point; and cor' .respondingly, said displacement will be increasing up to the middle point of the slot 32 and decreasing in the same proportion after passing the same. Therefore, although there is a certainv amount of flow of the fluid in the slots 3| and 32, nothing is being pumped from the conduit or into the conduit I2. The above position is the position for the no-discharge operation of the pump, While the position shown in Fig. 1 indicatesl the setting of the pump 20 for operation atits maximum capacity. Any intermediate position of said line of eccentricity ai-'awill effect a displacement of the pump, which is below its maximum, and will cause the pump to operate at some intermediate capacity.

The control valve 4|) comprises a valve body 4| provided with a cylindrical bore 42 adapted to receive a slidable member 50. At its ends, the valve body 4| is provided with covers 43 and 4,4. A conduit I6 provided with a manually operated valve 39 passes through the coverf'43 and connects the valve spaceadjacent to the cover 43 -With the discharge conduit I2. The slidable member has recesses 5|, 5|a, 52, 53 and 54 cut in its body, as shown in the drawings. The exi tended` end of the member 50 is provided, in the present instance, with means whereby manual operation of the valve 4|) is made convenient. Said means inthe present embodiment oi tne invention are exemplified in the form of a rack Vportion 56 engaging the gear portion 51 of the lever 58. By moving said lever 58, vthe slidable member 5I) may be set into any desired position Within the bore 42 of the valve body 4|.

The numerals 45,v 46 and I5a indicate escape openings through which the oil may escape into 'the storage tank. Conduits I3 and I4 connect the control valve 40 with the cylinder 60 leading, respectively, to the advance or pressure space 63 and to the back pressure space 64 of said cylinder 60. Conduit |4 has two parts I4a and I4b leading into the bore 42. When in` position of It will be noticed closest proximity to the conduit I3 the piston 6I is in its starting position. Pumping the oil through the conduit I3 into the space 63 causes the piston" to move toward the conduit I4, causing at the same time the rod 62 and other hydraulically actuated members to advance toward the work. When the piston 6I is at the end of its stroke near the conduit I4, the rod 62 is in its fully extended position. When the oil is pumped into the cylinder 6l through the conduit I4, the piston 6I returns to its starting position.

The valve 39 comprises a suitable valve body in which there is slidably fitted a recessed piston 33a. Conduit I6 eii'ects a constant communication of the end space of the governor valve 40 with the space formed by the recess in said piston 33d, while the waste port I 6a is provided for the purpose of releasing the oil which may be entrapped in said end space, thus relieving the pressure in said space and permitting free move ments of the slidable member 50 into any desired position. The piston 33a may be voperated either independently, or may be operatively connected with theY lever 58 in such way that when said lever 58 is in the position shown in Figs. ,3 and 8, it moves the piston 33a into the position shown in said .figures Such an arrangement may be easily effected by disposing the valve 38 parallel to the valve 40 and connecting the piston 33a to a suitable gear portion mounted'on the shaft of the lever 58.

The back-pressure space 64 is connected with the aid of conduits I1, I1 to thermetering device 10. Said metering device is arranged at the shaft 25 of the pump 20, as shown in Fig. 2. Fig. 1 shows the device in a diagrammatic way in a position away from the pump, in order to illustrate the nature of the hydraulic cycle more clearly. The metering device 10 comprises a casing 1I enclosing the articulated end of the shaft 25 Aand having passageways 12, 12 and 13,

, 13 provided in its body. 'I'he end of the shaft 25 is provided with a concentric hole 25m and a transverse slot 15. An end piece 16 of the same diameter as that of the shaft 25, provided with a cylindrical portion adapted to engage the hole 25a and a milled portion adapted to engage the slot 15, is held in the end of the shaft 25. Moving the piece 16 out of said end will form two pockets 14, 14 between its body and the body of the shaft 25, the size of said pockets depending upon the position of the piece 16. In operative position, the end piece 16 is held between the spring 18 and a regulating screw 13. By adjust-l ing the screw 19, the size of the pockets 14, 14 may be changed and their capacity varied from zero up to a certain predetermined limit. The passageways 13, 13 lead to free escape openings, while the passageways 12, 12 are connected with the conduits I1, I1, and through the conduit I4 with the back-pressure space 64 of the cylinder 60. The pockets formed by the end piece 16 as they revolve through each 90 angle register alternatively with thepassageways 12, 12y hydraulically connected with the back-pressure side of the cylinder 60, and with the passageways 13, 13 leading to free escape openings as mentioned.

From the foregoing it will be appreciated that ifoil is forced under high pressure into the conduits I1, I1 the pockets 14 will be filled each time they register with the passageways 12, 12.

tion of the pockets 14, 14. Thus, the metering device 16 will operate to"meter olf the oil at a certain predetermined rate depending upon the rotative speed of the shaft 25 and the adjusted capacity of the pockets; By adjusting the regulating screw 'I3 andchanging the size of the pockets, the rate lof discharge through the metering device 18 may be varied within predetermined vlimits in any desired degree.

In operation of my novel device, when it is desired to eil'ect 'a rapidv advance of the piston 6I, the control-valve 4l is set with the aid of the lever 58 as shown in Fig. 4. In this condition, Y the pump 28 will pump the oil through the conduit I2, recess 53 and conduit I3 into the pressure space 63 of the cylinder l6I). The oil from the back-pressure space 64 will be allowed to escape through the conduit I4, recess 52, and escape opening 45 into the storage tank. With the spring 38 holding the piston 35 in its fullyvextended position, the pump 20 will operate at its full capacity and under a very slight'pressure,

effecting a rapid advance movement of the piston 6I and the rod 62. f

If it is desired to change the rapid advance movement of lthe rod 62 into a .slow feeding movement, the member 53 of the control valve 40 is shifted with the aid of the lever' 58 into the position illustrated in Fig. 1. In this condition, the free escape opening 45' will be out oif from the conduit I4, and the oil contained in the back-pressure space 64 will not be permitted to escape. This will immediately deter the rapid advance movement of the piston 62. Since in this condition the space 64 is communicating through conduit I4, port I 4b, recess 5I, and conduit I5 with the cylinder 34, back-pressure built up in the space 64 will be transmitted into the cylinder 34. Piston will be moved against the compression of the spring 38, and acting through the rack 36, it will begin moving the ring 22 into theposition shown in Fig. 3. Now the oil from the space 64 will be metered ou by the metering device 10 in accordance with the adjustment thereof, and will permit slow feeding movement of the piston 6I and of the piston rod 62. In this condition, the pump will have a rate of discharge just Isuilcient to maintain vthis position. If it becomes necessary to return the piston 6I into its starting position, the same may be done rapidly by moving the lever 58 so as to 'set the sliding member 56 into the position shown in Fig.,5. In this condition, the oil will be pumped through the discharge conduit I2, recessv 53, and conduit I4 into the space 64, moving the piston 6I toward its starting position, the oil from the space 63 being permitted to escape through the'conduit I3, recess 54, and opening 46 into the storage tank.

l In order to set the pump for idling operation,

the valves 39 and 4II`are set in the positionsshown 'in Fig. 3. In this-condition, no oil will be pumped into or allowed to escape from the y cylinder 6I), and this will stop any movement of the piston 6I. At the same time, the entire discharge of the pump 20 will be directed through the conduit I6, valve bore 42 and conduit I5 into the cylinder 34. With the piston 35 moved all the way into the cylinder the pump will be set for no-discharge operation. It should be noted that Fig. 3 shows the position of the piston 35 after said action has taken place, and the piston 35 is moved from its retracted positiony to the position shown. During the nrst` few moments following moving of the member 5l to all volume and pressure of the entire discharge of the pump being directed through the conduits I2, I and I5 into the cylinder 84 and caused to act on said piston 85, said piston begins to move 35, the pressure of the spring 38 will immediately cause the piston 35 to move toward its retracted position, whereby the discharge ot the pumpA automatically increases until the balanced condition is reestablished.

It will be noted that in certain instances it is necessary to release the oil which' may be entrapped in the cylinder 84, in order to permit the movement of the piston 85 into its retracted position. This necessity arises, for instance, when the valve setting is changed from a feeding movement to a rapid return movement.

f Means for permitting the oil entrapped in the cylinder 38 to escape are exemplified in the present embodiment by the recess 5i a, and the Waste port IEc. From an examination of Fig. 5 it Will become apparent that when the slidable member 58 is shifted into the position for rapid return movement of the operating piston, the oil fllling the cylinder 34 will escape through the conduit i5, recess 5I and waste port i5a into the storage tank. Also, when the valve setting is changed from idling to rapid advance (see Fig. Li), the oil from the cylinder will escape through the conduit i5, recess 5ta, and waste port ita'into the storagetank. When the valve setting is changed from idling to rapid return (see Fig. 5), the oil from the cylinder 34 will escape through the `conduit I5, recess 5I and Waste port ita.

It will also be noticed that in ali operative settings of the valve MJ, the end space thereof adjacent to the recess Sla is inoperative and it communicates with the storage tank through oil in said space.

the conduit I8, recess of the piston 39a, and waste port Ita, thus preventing entrapment of In the modified structure embodying my invention, shown in Figs. 6 to 8, inclusive, the general character of the cycle employed, and the operation of thedevice is similar to that of the preferred structure. However, in this structure I employ different means for controlling the discharge of the pump, designated generally by the numeral 80. In this structure, the pump body 8| houses a concentric pump ring 82 cooperating with the rotor 86 keyed onto the shaft 85, said rotor having a plurality of blades 88 sliding in longitudinal radial slots 81. Operation of the rotor 88 and blades 88 is similar to that of the rotor 26 and blades 28 of the preferred structure. Change of the displacement of the pockets formed by said blades 88 is effected in this structure by changing the amount. of eccentricity of the axis of theV ring 82 with respect to the axis of the rotor 86. When it is desired to have the pump 80 operate at full capacity, the ring 82 is moved into the position shown in Fig. 6, where the amount oi' eccentricity is the largest. On the other hand, when it is desired to operate the pump at no-discharge", the `ring 82 is bodily the position shown in Fig.- 3, the piston 85 is in its retracted position shown in Fig. 1. However,

concentric position. therewill be no relative eccentricity of the rotor 88land the ring 82, and the displacement of the pockets formed by the blades 88 remains constant during the rotation` of the rotor and in such condition no oil is drawn from the slot 8l or forced into thel slot 82. Any intermediate position of the ring 82 produces a condition in which the pump 80 operates at a respective intermediate capacity. n Means are provided in this structure for moving the ring 82 and, comequently, changing the volumetric displacement of the pump 88 automatically by the fluid itself in accordance with the pressure in the circuit. 'I'he ring 82 has at its outside cylindrical surface four milled flat portions. lwo of them are intended to adapt it for cooperation with the guiding hats 83 and 84 of the pump body 8l, While the other two, eut at an angle of 98 to those cooperating with the surfaces 88 and 84, are adapted to bear the pressure of pistons 85 and 86. The piston 95 is adapted to operate in an eccentricity-decreasing cylinder 93 cast integrally with the pump body 8i, and the piston 88 is adapted to operate in the. eccentricity-restoring cylinder 9d integral with the pump body 8|. Piston 85 has a larger diameter than has the piston 96, and therefore with the same pressure in both cylinders, the piston will exert upon the pump ring 88 a much greater force than will the piston B5. The cylinder 94 is connected by means of the conduit i8 with the discharge conduit i2. .The piston 88 is aided in its movement toward the rotor 88 by a spring 8l, the initial compression'of whichis regulated with the aid of a screw 98.

For the rapid advance of the piston ii i the con trol valve is set in position' illustrated in Fig. li.

' 'The ovv oi the oil in this condition is as indicated by arrows, it being pumped into the space tit of the cylinder '68 and allowed to escape freely from the space 64 through the escape opening 45. In

`this condition there will be no pressure built in the cylinder 93, while there will be some pressure transmitted from the discharge conduit i2 into the cylinder 94. Aided by the spring 91the piston 98 is capable in this condition `to exert a sufficient force to move the ring 82 all the way toward the piston 95 until it reaches the stop 93a. In this position of the ring 82, the eccentricity will be greater, and the pump will operate at its maximum capacity, effecting a rapid movement of the piston 6i. To change the rapid movement of the piston 6| into a slow feeding movement, the control valve is set in the position shown in Fig. 6. In this condition the free escape opening 45 is closed, and the cylinder 83 is communicating with the back-pressure space 64. The free escape of the oil being prevented, the piston 6l ceases to move, and pressure is built up in the space 63, space 64, and in the cylinder 9 3. Because of the pressure in the cylinder 93, the piston 85 operates to move the ring 82 toward a position of de creased eccentricity, causing the pump 88 to decrease the rate of its discharge. The back-pressure in the space 84 is relieved in this condition only because of the operation of the metering device 18, and it is the rate of this metering off action of the device 'l0 that determines the rate of the feeding movement of the piston 6I, While the amount of eccentricity of the ring 82 determines the rate of discharge of the pump 80. In other words, the back-pressure in the space 64 of pump discharge as to correspond to the rate of metering action of the device 10. Of course, the pump must be tested and regulated with the aid of the screw 98 to produce in these conditions such a balanced action.

Rapid return movement of the piston 6I is produced when the control valve is set in the position shown in Fig. 5, in which condition no pressure will be applied to the piston 95, and the pump will operate at increased capacity, pumping oil into the space 6I, while the voil from Vthe space 63 will be allowed to escape through the opening 46 into the storage'tank.

For idling operation the valves 39 and 40 are set as illustrated in Fig. 8. In this condition the entire discharge of the pump 80 is directed into the cylinders 83 and 9|, but., because of the difference in the respective piston areas, a much greater force is exerted by the piston 95, and it moves the ring 82 into the position of exact concentricity with the rotor 86, in which condition the pump 8U does not produce any discharge.

The oil which may be entrapped in the cylinv der 93 is released by operation of the means describedy in connection with the preferred structure, and their separate description is dispensed with for the above reasons.

It will be noted that, with the exception of the position for idling operation of the pump, the valve Ill'is hydraulically balanced, that is all hydraulic forces applied thereto will balance each other and, consequently, there is no necessity of firmly locking the sliding member 50 in any of the positions. Also, the resistance of said member 50 to manual operation will be limited to the mere friction.

'Ihus in one of its broader aspects my invention contemplates providing a novel hydraulic device rfor hydraulic feeds and controls, in which the rate of intake and discharge of the pump are changing in accordance with the discharge requirement for a particular type of movement ot the hydraulically actuated member, and in which said change of intake and discharge is effected automatically by the pressure of the liquid fluid Itself.

Although only two embodiments of my invention have been illustrated and described, other changes and modications in the for'm and arrangement of parts, which will now appear to those skilled in the art, may be made without departing from the scope of my invention. For instance, other means for changing the encentricity of the pump `than those employed in the hereindescribed embodiment may be used. Other types of pumps, such as reciprocating pumps of valve may be employed.

I claim:

i. In a hydraulic device for eiecting hydraulic feeds or the like, a pump of variable discharge, an operatingcylinder, a piston reciprocable in said cylinder and actuated by the pressure of discharge of said pump, and means operated at a predetermined time by the back pressure created in said -cylinder by said piston for changing the rate of discharge of said pump in substantially inverse proportion to the magnitude of said back pressure.

2. In a hydraulic device for effecting hydraulic feeds or the like, a pump of variable discharge, an operating cylinder, a piston reciprocable in said cylinder and actuated by the pressure of discharge of said pump, and means including a reciprocable spring actuated piston operated at a predetermined time by the back pressure created in said cylinder by said piston for changing the rate oi discharge of ysaid pump in substantially inverse proportion to the magnitude of said back pressure.

3. In a hydraulic device for effecting hydraulic feeds or the like, a pump of variable discharge, an operating cylinder, a piston reciprocable in said cylinder and actuated by the pressure of discharge of said pump, means operated at a predetermined time by the back pressure created in said cylinder. by said piston for changing the rate of discharge of said pump in substantially inverse proportion to the magnitude of said back pressure, valve means adjustable to preclude operation of said means by the back pressure, and means for metering off the fluid at a predetermined rate from the back pressure side of said cylinder.

4. In a hydraulic device for eifecting hydraulic feeds or the like, a pump of variable discharge, an operating cylinder, a piston reciprocable in said cylinder and actuated by the pressure of discharge of said pump, means operated at a predetermined time by the back pressure created in said cylinder by said piston for changing the rate of discharge of said pump in substantially inverse proportion to the magnitude of said back pressure, valve means adjustable to preclude operation of said means by the back pressure, and rotary means for metering oir the duid by centrifugal action at a predetermined rate from the back pressure side of said cylinder.

5. In a hydraulic device for effecting hydraulic feeds and controls, a pump of variable discharge,'

an operating cylinder with a piston, said piston adapted to be actuated by the pressure of dissharge of said pump, and a member operated by back pressure created in said cylinder by said piston, said member adapted to change the rate of discharge of said pump in inverse proportion to the magnitude of said back pressure.

6. In a hydraulic device for eilecting hydraulic feeds and controls, a pump of variable discharge, I an operating cylinder having a piston adapted to b e actuated by the pressure of discharge of said pump, a discharge-controlling cylinder having a piston adapted to be operated by back pressure created in said operating cylinder by said operating piston and mechanically connected with the discharge-controlling element of Vsaid pump, whereby the discharge of said pump decreases in proportion to the increase of said back pressure.

'7. In a hydraulic device for eifecting hydraulic feeds and controls, a pump of variable discharge, an operating cylinder having a piston adapted to be actuated by the pressure of discharge of said pump, a discharge-controlling cylinder having a piston adapted to be operated by back pressure created in said operating cylinder by said operating piston and mechanically connected with the discharge-controlling element of said pump, whereby the discharge of said pump decreases in proportion to the increase of said back pressure, and means acting in opposition to said discharge-controlling piston and adapted to move the vsame into the position corresponding to the full capacity of the pump when hydraulic communication between said discharge-controlling cylinder and the back pressure-space of the operating cylinder is interrupted.

8. In a hydraulic device for effecting hydraulic lll) p operatively feedsand controls,` ax positive acting pumpl of variable volumetric displacement, an operating cylinder having a piston adapted to be actuated by the pressure of discharge of said pump, a dls placement controlling cylinder having a piston arranged therein and adapted to be operated by back pressure created in said operating cylinder by the movement of said operating piston, said displacement-controlling piston being operatively connected to the displacement-affecting means of said pump, whereby the volumetric displacementof said pump decreases in proportion to the increase of said back pressure, and a spring acting in opposition to said displacement controlling piston and adapted toinove the same, when hydraulic communication between said displacement-controlling cylinder and the baci; pressure space of the operating cylinder is interrupted, into the position effecting a displacement corresponding substantially to that of the full capacity of the pump.

9. ln a device vfor effecting hydraulic feeds and controls, a rotary pump of variable volumetric displacement, an operating cylinder having a piston slldably arranged therein, .said piston adapted to be selectively advanced from one end of the cylinder to the other and to be returned to the starting position by the pressure of the duid discharged by said pump, a displacement-controlling piston operatively arranged in a suitable cylinder and adapted to respond to the back. pressure created in said operatingcylinder because' of the advance movement of said operating piston and to decrease the volumetric displacement of said pump when said back pressure increases, and a spring acting in opposition to said displacement-controlling piston and adapted to move the same into a position effecting a displacement corresponding substantiallyr to that of the full capacity of the pump when a substantially atmospheric pressure is caused to operate upon saiddisplacement-controlling piston.

ll). lin a device for effecting hydraulic feeds and controls, a rotary pump including a rotor and an eccentricity ring encircling said rotor, said ring adapted to change, as its eccentricity is affected, the volumetric displacement of said pump from zero to displacement corresponding to full capacity of the pump, an operating cylinder having a piston operatively arranged therein, said piston adapted to be selectively advanced from one end of the cylinder to the other end thereof and to be returned to its starting position by the pressure of fluid discharged by said pump, an eccentricity-controlling piston operatively arranged in a suitable cylinder and adapted to respond to the back pressure created in said operatingy cylinder because of the advance movement of said operating piston and to affect theeccentricity of said eccentricity ring, thereby decreasing the volumetric displacement of said pump as said back pressure increases, and a spring acting in the direction opposite to that of said eccentricity-controlling piston, spring adapted to affect the eccentricity of said ring andto increase thereby the displacement of said .pump as said back pressure decreases, and to effect the displacement corresponding to the full capacity of said pump vwhen said eccentricity-controlling piston is not subjected to said back pressure.

11. A device for effecting hydraulic feeds or the like, comprising a rotary pumpof 'variable volumetric displacement, an operating cylinder having a piston arranged therein and adapted said v to be moved into advance position yand to be 'returned to' its starting position by the fluid pressure created by said pump; a metering device operated by the rotor of said pump, hydraulically connected to the back pressure side of said cyllnderand adapted to meter off the fluid from the back pressure side Aof said operating cylinder at a predetermined rate.

12. A device for effecting hydraulic feeds or the like, comprising a rotary pump of variable volumetric displacement, an operating cylinder having a piston arranged therein and adapted to be moved into advance position and to be returned to its starting position by the fluid pressure created by said pump, a metering device operated bythe rotor of` said pump, hydraulically connected to the back pressure side of said cylinder and adapted to meter off the iiuid from .the back pressure side of said operating cylinder at a predetermined rate, a displacement-controlling piston operatively arranged in a suitable cylinder and adapted to respond to the back pressure created in said operating cylinder because of the advance movement of said operating piston and to effect in said pump a displacement producing a rate of discharge equal to that off the metering off rate of said metering device.

i3. ll device for effecting hydraulic feeds or the like, comprising a yrotary pump of variable volumetric displacement, an operating. cylinder having a piston arranged therein-and adapted to be moved into advance position and to be :returned to its starting position by the fluid pressure created by said pump, a metering device operated by the rotor of said pump, hydraulically connected to the.back pressure side of said cylinder and adapted to meter off the fluid from the bacia pressure side of said operating cylinder at a predetermined rate, a displacement-controlling piston operatively arranged in a suitable cylinder and adapted to respond to the baci: pressure created in said operating cylinder because ofthe advance movement 'of said operating piston and to effect in said pump a displacement producing a rate of discharge equal to that of the metering olf rate of said metering device, a member acting in opposition to said displacement-controlling piston and adapted to effect maximum displacement in said pump when there is no communication between the back pressure side of said operating cylinder and said displacement-controlling cylinder.

i4. A device for effecting hydraulic feeds or the like,v comprising a rotary pump of variable volumetric displacement, an operating cylinder havingr a piston arranged therein and adapted to be moved into advance position and to be returned to its starting position by the fluid pressure created by said pump, a rotary metering device operated by the rotor of said pump, said device being hydraulically connected to the back pressure side of said cylinder and adapted to meter ofi the fluid by centrifugal action from said back pressure side at a predetermined rate.

15. A device'for effecting hydraulic feeds or the like, comprising a rotary pump of variable volumetric displacement, an operating cylinder having a piston arranged therein and adapted to be moved into advance position and to be returned to its starting position by the fluid pressure created by said pump, a rotary metering device operated by the rotor of said pump, said device being hydraulically connected to the back pressure side of said cylinder and adapted to meter off the fluid by centrifugal action from said back -an end piece fitting into the end of the rotor shaft and forming pockets of adjustable volume, said pockets adapted in operation to register alternatively with said back pressure passages and with said free escape passages, whereby the fluid is metered oi from the back pressure side or said operating cylinder at a predetermined adjustable rate.

17. In a device for effecting hydraulic feeds 4 and controls, a rotary pump having a pump body provided .with an intake slot and a discharge:

slot, a concentric rotor with a plurality of blades operatively arranged in said pump body, and an eccentricity ring of constant eccentricity encircling said rotor vand adapted to be moved so as to change the position o! its eccentricity with respect to said slots thereby changing the volumetric displacement of said pump, an operating cylinder having a piston adapted to be selectively advanced from one end of the cylinder to the other end thereof and to be returned to its starting position by the pressure of fluid discharged c ing the volumetric displacement of said pump as said back pressure increases, and a spring acting in the direction opposite to that of said eccentricity-controlling piston and adapted t0 move said eccentricity ring and to increase thereby the displacement of said pump as said back pressure decreases, and to eiect the displacement ccrresponding to that of the full capacity of said pump when said eccentricitycontrolling piston is not subjected to said back pressure.

MAX J. CLARK. 

